Steam boiler



Sept. 24, 1935. D. s. JACOBUS (ET AL 2,015,362

STEAM BOILER Filed Dec. 1, 1932 3 Sheets-Sheet l INVENTORS Dal/id S Jacob'us B Robert [C Behr ATTORNEY v P 1935. D. s. JACOBUS ET AL 2,015,362

' STEAM BOILER Filgd Dec. 1, 1932 3 Sheets-Sheet 2 INVENTORS David '5. Jacobus BY Robert lCBe/zr Sept. 24, 1935. D; s. JACOBUS El AL STEAM BOILER 3 Sheets-Sheet 3 Filed Dec. 1, 1932 INVENTORS 0.000000 000 0000 O AvODOOOQ 0000000 a Y .m 2 d .m w A R Patented Sept. 24', 1935 UNITED .STATES PATENT OFFICE 2,015,362 STEAM BOILER.

Application December 1, 1932, Serial no. 645,162

25 Claims.

The present invention relates to the construction and operation of water tube steam boilers, and particularly to boilers of that type which are characterized by the arrangement of fluidheating surface in the space above a main bank of steam generating tubes and between the circulator tubes which provide a natural fluid circulation between that bank and an elevated steam and water drum and aid in defining the front and rear walls of the portion of the boiler above the main steam generating tube bank. The invention is especially applicable to the construction of water tube boilers in which the steam and water drum is located at a substantial distance above 1 the uppermost point of steam generation in the main tube bank, whereby a rapid natural circulation of the fluid through the tube bank is maintained by the high hydraulic head to which it is subjected.

The general object of our invention is the provision of a water tube steam boiler of the general character described which is further characterized by its relatively low cost of construction,-

economy of maintenance and operation, relatively high steaming capacity, and small amount of floor space required. A further and more specific object is the provision of a high drum water tube boiler with an, improved construction and arrangement therein of the fluid heating 30 surface supplemental or auxiliary to the natural circulation steam generating bank by which high rates of heat transference to the supplemental surface are maintained, tube replacement is facilitated, tubes of relatively short horizontal extent may be used, and an effective arrangement for supporting the tubes provided.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described preferred embodiments of our invention.

Of the drawings:

Fig. 1 is a somewhat diagrammatic sectional 50 elevation of a water tube steam boiler constructed in accordance with our invention, certain parts being omitted for purposes of clarity;

Fig. 2 is a detail on an enlarged scale of a portion of the boiler shown in Fig. 1;

55 Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a view on an enlarged scale of a. tube connection shown in Fig. 1;

; Fig. 5 is a view similar to Fig. 1 of a modification; and

Fig. 6 is a view similar to Fig. 1 of a second 6 modification. V

In the steam boiler illustrated in Figs. 1 to 4 of the drawings, I0 designates a combustion chamber formed by walls I] provided with cooling tubes l 2 covered by blocks and connected into 10 the boiler circulation as hereinafter described. Powdered fuel is supplied to the combustion chamber through fuel burners l3 in one of the walls thereof along with preheated air for combustion. The air is preheated in an air heater l4 l5 and delivered through a 'duct l5 having branches l6 leading to a' chamber l1 surrounding the fuel burners. Dampers l8 control the supplies of air to the chamber H.

The high temperature heating gases pass up-, 20

wardly from the combustion chamber it into contact with fluid heating surface arranged as hereinafter described. Most of the solids carried by the heating gases are separated out by rows of horizontally spaced furnace slag screen or dust collecting tubes 20 extending across the upper part of the combustion chamber. The tubes 20 have their ends connected to external headers 2| and 22 and are provided with a refractory covering. In operation, the tubes 20 will ordinarily have a coating of molten slag which aids in collecting the solid particles. The headers 2i and 22 are connected into the boiler circulation by tubes 23 and respectively.

Extending across the upper end of the com bustion chamber is a bank of horizontally inclined tubes 25, the lower rows of which are further spaced apart vertically and/0r horizontally than the upper rows to form a boiler slag screen.

The tubes 25 are arranged in side-by-side sections and their ends are connected to corresponding downtake and uptake headers 26 and 21 respectively. A rapid natural circulation of the heated fluid is maintained through the tube bank 25 by the arrangement of a horizontal transverse steam and water drum 28 suspended at a substantial distance above the highest point of steam generation in the tube bank 25 and by downtake and uptake circulator tubes 29 and 30 connecting the drum 28 to the downtake and uptake headers respectively. The circulators 29 and 30 extend vertically from the headers, and in conjunction with refractory material 3|, form fluid cooled walls defining the rear and front walls respectively, r the portion of the boiler above the tube bank 25. Horizontal portions 30 of the uptake circulators define the roof of the boiler. The uptake circulators 30 are supported from above by suitable rods 30 welded to the upper ends of their vertical portions, while the downtake circulators are carried by the drum 28. The combustion chamber wall tubes l2 are connected to the drum 28 by riser tubes 32 arranged at the outer sides of the boiler wall portions heretofore mentioned.

With the boiler constructed as described, a gastight space of substantial height and volume is available above the tube bank 25 and between the uptake and downtake circulators, in which most, if not all, of the supplemental or auxiliary fluid heating surface of the boiler may advantageously be located. In accordance with our invention a high mass flow of heating gases past the heating surface without decreasing the permissible latitude in tube spacing is obtained as well as other advantages hereinafter pointed out by dividing the space above the tube bank and between the circulator rows into successive upfiow and downflow gas passages 40 and 4| connected for a series flow of heating gases therethrough. As shown in Figs. 1, 2 and 3, the gas passages are formed by a partition 33 extending inwardly and upwardly from the rear wall of the boiler and terminating at a level below the bottom of the drum 28. The partition is formed by refractory blocks 33 backed by plates 33 having their flanged edge portions connected. The partition is cooled and supported in its desired position by one or more rows of steam generating tubes 25 extending from the uppermost rows of tube openings in the downtake headers upwardly along the inner face of the partition, and having their upper ends connected to an intermediate header 34 horizontally arranged in the vertical portion of the partition 33.

The tubes 25* are advantageously connected into the boiler circulation by a lesser number of tubes 35 extending between and spaced along the header 34 and drum 28. The partition is suspended from the external frame-work by rods 38 welded to the bent portions of the tubes 35.

Thus the heating gases from the combustion chamber will first pass over the tube bank 25 and then upwardly through the gas passage 40, over the upper end of the partition 33 and across the tubes 35, and then downwardly through the gas passage 4|. As shown in Figs. 1 and 2, alternate downtake circulators are bent laterally to increase the gas flow area between adjacent tubes, and the wall-forming refractory material 3| associated with the inner row of downtake circulators terminates at a level corresponding to the lower end of the vertical portion of the partition 33, to form a gas outlet 42. The outlet 42 is connected to the heating gas flow passages of the air heater I4 and the gases after passing therethrough are discharged to a stack connection 44.

- The supplemental or auxiliary fluid heating surface of the boiler-is divided into a steam superheating section and a water heating section, and the respective sections arranged so as to be subjected to the most desirable heat transfer conditions. As shown in Fig. l, the steam superheating section is located in the first upflow gas passage and divided into upper and lower units or sections 45 and 46 respectively, each comprising a bank of vertically looped side-by-side tubes with horizontal leg portions of relatively short length arranged in parallel vertical planes transverse to the planes in which the circulator and partition-supporting tubes are located. Adjoining leg portions in each bank are preferably connected in any suitable manner to form a unitary structure which is supported from the uptake circulators 30 and partition supporting tubes 35 by lugs 41 on the looped portions of the superheater tubes. The ends of the looped tubes of the upper superheater section are connected to inlet and outlet headers 49 and 50 respectively, while the tubes of the lower section are connected to inlet and outlet headers and 52 respectively. Steam supply tubes 53 connect the drum 28 to the inlet header 5| of the lower section. The outlet header 52 is connected to a pipe 54 leading to a suitable regulable steam desuperheater 55, which may be of the character illustrated in the copending application of John E. Black, Serial No. 446,270, filed April 22, 1930, and the partly desuperheated steam is returned through a pipe 56 leading to the header 49 of the upper section. The steam at the desired degree of superheat passes from the outlet header 50 to a point of use. -Headers 49, 50, SI and 52 are supported independently of the bracket supports 41, 48, by suitable supports (not shown).

The water heating surface is advantageously located in the downflow gas passage 4| and preferably divided into upper and lower units or sections 60 and lil each also consisting of a bank of vertically looped side-by-side tubes having horizontal leg portions of relatively short length extending across the gas passage in vertical planes transverse to the planes in which the downtake circulators and partition-supporting tubes are located. Each economizer section is formed in a unitary structure and supported from the circulator and partition-supporting tubes in the same manner as the superheater tubes. By this distribution of the tube load, excessive strains on the downtake connections to the drum 28 are avoided. The lower ends of the tubes in the lower economizer section are connected into a supply header 62, which receives a supply of feed water at the desired pressure from a suitable feed pump (not shown) The upper ends of the tubes of the upper section are directly connected into the steam and water drum 28. An upward serial flow of the heated fluid is maintained between the two sections by connecting corresponding tubes in the lowermost row of the upper section to corresponding tubes in the uppermost row of the lower section. These tube connections are advantageously arranged within the space between the tube banks and are formed by threading the ends of each pair of tubes 60 and GI, as shown in Fig. 4, and connecting the threaded ends by a coupling 63. Each coupling is seal welded to the corresponding tubes as indicated at 64. The use of expensive externally located return bends is thus avoided. a

The described arrangement of the tubes in the superheater and economizer sections permits rapid replacement of any of those tubes. The tubes are withdrawn through the spaces between adjacent uptake or downtake circulators and then through openings left by removable panels in the outer casing 64 of the boiler. To expedite 65 the replacement of the economizer tubes, access doors 65 are provided in the portion of the side walls opposite the interbank space providing access to the couplings 63. These openings may also be used for access to the handhole openings in the header 34 and for the insertion of steam lances or other tube cleaning equipment.

The inclined portion of the partition 33 is preferably arranged at an angle greater than the angle of repose of the solid residue which tends the space between the lower ends of the downtake circulators and the lower end of the partition 33 and cause corrosion of the headers and of the circulator connections thereto. To avoid the formation of a dust pocket in this portion of the boiler the partition 33 is provided with a rearward extension 66 formed by spaced plate members 81 surrounding the lower portions of the downtake circulators, the interplate space being packed with insulating material 88. With this arrangement theinclined surface of the partition is continued to a point beyond the downtake circulators. Plates 69'extend between the upper ends] of the headers 26 and the partition extension 66', closing that side of the pocket.

With a steam boiler constructed as described, fuel may be burned'in the combustion chamber It at relatively high rates of B. t. u. release, and high temperature heating gases pass upwardly across the slagscreen tubes 29, by which a large portion of the solid material carried by the gases is removed. Combustion may continue in the space between the tubes and tube bank 25. The heating gases pass upwardly over the entire length of the tubes 25. The mass flow of-heating gases is substantially increased in the upper portion of the boiler while maintaining a desirable latitude in tube spacing and with a minimum increase in draft loss, by the division of the space above thetube bank and between the circulators into several gas passages. The mass flow will progressively increase during the passage of the gases through the tapering lower portion of the first upflow passage. The arrangement of the superheating surface in the narrowest portion of the upflow gas pass with a parallel flow of the heating gases and heating fluid will afford a maximum heating effect with maximum safety from tube overheating. The steam generated in the furnace water walls and tube bank 25 and any steam that may be generated in the upper part of the economizer section 88 is delivered to the drum 28 fromwhich it passes to the superheater inlet header 5|. The degree of superheat may be accurately controlled and the metal'temperatures of the superheater tubes in the upper superheater section maintained within the permissible limits by the interposition of the regulable desuperheater 55 between the headers 52 and 49. The steam after being partly desuperheated will be again raised in temperature while passing through the upper section 45. Explosion doors 1!! of any suitable type are provided in the roof of the boiler to relieve any excess pressure which may develop in the furnace and passage 40 due to possible explosive combustion of the fuel.

The counterflow arrangement of the economizer in the downflow gas passage. is particularly advantageous. Withthis arrangement the heating gases will progressively decrease in temperature during their downward flow, while the temperature of the feed water will progressively increase during its upward passage through the tubes.

sage 4! takes advantage of the natural tendency .of the heating gases on cooling to flow down- The economizer surface is of relatively high heat absorptive capacity as compared to the wardly. The arrangement of the economizer tubes containing the highest temperature fluid at the highest level avoids opposition to fluid flow therethrough when steam is generated in the upper section. the several economizer tubes is, substantially improved by their separate connections with the drum 28. The heating gases leave the downflow passage through the outlet 42, passing across the lower portions of the downtakecirculators 10 to the air heater l4, in which the air for combustion is preheated by the gases flowing to the stack connection 44.

In the modification illustrated in Fig. 5, the upflow gas passage 40 contains only a single bank 15 of superheater tubes 80, the remaining portion of that passage being occupied by the first or inlet section 8| of the economizer. The second or discharge economizer section 82 islocated in the downflow passage with its lower end 0011- 29 nected to the first economizer section by tubes 83. Feed water supplied to the upper header 84 of the first economizer section-flows downwardly through the tubes in the upflow gas passageand thence to. the lowermost tubes in the downflow 25 gas passage. The upper ends of the tubes in the section 82 are directly connected to the steam and water drum 28. The construction and mode of operation is otherwise similar to that heretofore described.

In the modification illustrated in Fig. 6, the space above the tube bank 25 is divided into three passages, and the heating gas outlet 90 located in the top of the boiler. The heating gas passages are formed by fluid cooled partitions SH and 92, the partition 9| extending inwardly and upwardly from the rear wall of the boiler and cooled and supported by rows of tubes 93 and 94. a The tubes 93 have their lower ends connected to the upper portion of the down- 40v the steam' and water drum 28 by horizontal tubes 91. The partition 92 is carried on the upper portions of tubes 98 extending vertically from theheader 95 and having their upper ends connected to the drum 28. By this partition arrangement the space between the uptake and downtake circulators and above the tube bank' will be divided into two upflow gas passages I08 and NH and an intermediate downflow gas passage lll2, all arranged in series. The first upflow gas passage is occupied by a steam superheater of the type heretofore described, receiving its supply of steam from the drum 28 through tubes I03. The remaining gas passages are occupied by economizer sections I04 and I05, the tubes of which extend across the width of the boiler. The economizer sections are arranged for a. series flow therebetween through tubes I06. The economizer is of the counter-flow type, feed. water being supplied to the upper header of the I section I05 through a pipe I01 and the uppermost tubes of the section I04 directly connected to the drum 28. The boiler construction and mode of operation are otherwise similar to that shown in Fig. 1. i

It will be observed that in each of the boiler constructions described, the convection heating surface is divided into separate sections contain- Equalization of flow conditions in 5 stantially completed before the heating gases contact with the succeeding section. The surface first contacted by the gases contains a fluid at substantially constant temperature, while the re- ..-5 maining surface contacted contains fluids progressively increasing in temperature and as such, advantageously located in the zones of greater mass flow, with the surface containing the fluid to be heated to the highest temperature confined 10 t the first passage. By this serial absorption of heat by surface containing different fluids, it is possible to most economically arrange the heating surface, i. e., use a minimum amount of heating surface for a required heating effect, while ob- I' taining maximum safety against overheating of the tubes.

While in accordance with the provisions of the statutes we have illustrated and described herein the best forms of our invention now known to 20 us, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes 2'5 be used to advantage without a corresponding use of other features.

We claim:

1. A steam boiler comprising a combustion chamber, a horizontally inclined bank of steam 30T generating tubes arranged across the path of the heating gases leaving said combustion chamber, a horizontal transverse steam and water drum positioned a substantial distance above the uppermost point of steam generation in said tube bank, uptake and downtake circulators connecting said drum to opposite ends of said tube bank and providing a rapid natural fluid circulation between said drum and'tube bank and respectively defining the front and rear walls of the upper 49: portion of said boiler, a partition extending inwardly and upwardly from the rear wall of said boiler and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas 45: passages arranged in series, a row of partition-supporting tubes extending upwardly from said downtake headers in heat absorbing relation with said partition and having their upper ends connected to said drum, a bank 50 of fluid heating tubes positioned in said upflow tubes arranged across the path of the heating gases leaving said combustion chamber, rows of uptake and downtake headers connected to opposite ends of said tube bank, a transverse steam and water drum positioned directly above said downtake headers and a substantial distance above said tube bank, vertically arranged uptake and downtake circulators connecting said drum and headers and providing a natural fluid circu-' lation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, a partition extending. inwardly and upwardly from the rear wall of said boiler and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages arranged in series, a row of partition-supporting tubes extending upwardly from said downtake headers in heat absorbing relation with ,,5 said partition and having their upper ends connected to said drum, a bank of looped fluid heating tubes positioned in said. upflow gas passage, means for supporting said looped tube bank from said uptake circulators and partition-supporting tubes, a second bank of looped fluid heating tubes positioned in said downflow gas passage, and means for supporting said second looped tube bank from said partition-supporting tubes and downtake circulators. 16

3. A steam boiler comprising a combustion chamber, an inclined bank of steam generating I tubes arranged across the path of the heating gases leaving said combustion chamber, uptake and downtake headers connected to opposite ends 20 of said tube bank, a steam and water drum positioned'above said tube bank, uptake and downtake circulators providing a natural fluid circulation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, a row of sup porting tubes extending inwardly and upwardly from said downtake headers and having their upper ends connected to said drum, means for suspending said row of supporting tubes, fluid heating tubes positioned in the upper portion of said boiler, and means for jointly supporting said fluid heating tubes from said supporting tubes and circulators. d

4. A steam boiler comprising a combustion chamber, an inclined bank of steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, a horizontal steam and water drum positioned a substantial distance above the uppermost point of 40, steam generation in said tube bank, uptake and downtake circulators'providing a natural fluid circulation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, a partition extending inwardly and upwardly from the rear wall of said boiler and dividing the space above said tube bank' and between said circulators into successive upflow and downflow heating gas passages, a bank of steam superheater tubes located in said upflow gas passage, means for supporting said superheater tubes from said uptake circulators, a bank of economizer tubes positioned in said downflow gas passage, and means for.sup.- porting said economizer tubes from said downtake circulators.

5-. A steam boiler comprising a combustion chamber, a bank of horizontally inclined steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, rows of uptake and downtake headers connected to opposite ends of said tube bank, a horizontal transverse steam' and water drum positioned a substantial distance above the uppermost point of steam generation in said tube bank, uptake and 6 downtake circulators connecting'said drum and headers and providing a rapid natural fluid cir-, culation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, partitions dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages arranged in series, rows of partition-supporting tubes in heat absorbingrelation with said partitions and having their upper ends connected to said drum, a bank of fluid heating tubes of relatively low heat absorptive capacity positioned in the first upflow gas passage, and banks of fluid heating tubes of relatively high heat absorptive capacity positioned in the remaining gas passages.

6. A steam boiler comprising a combustion chamber, an inclined bank of steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, a horizontal steam and water drum positioned a substantial distance above the uppermost point of ,steam generation in said tube bank, uptake and downtake circulators providing a natural fluid circulation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, a partition extending inwardly and upwardly from the rear wall of said boiler and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages, a steam superheater comprising upper and lower sections located in said upflow gas tors providing a natural fluid circulation between said drum and tube bank and respectively defining the front and rear walls of the upper portions oi. said boiler, a partition extending inwardly and upwardly from the rear wall of said boiler and dividing the space above said tube bank and between said circulators into successiveupflow and downflow heating gas passages, a bank of steam superheater tubes positioned in the lower portion of said upflow gas passage, and a counterflow economizer comprising a bank of economizer tubes positioned in the upper portion "of said upflow gas passage and a second bank of economizer tubes connected to said first bank for a series fluid flow therebetween and positioned in said downflow gas passage with their upper ends connected to said drum.

8. A steam boiler comprising a combustion chamber, a horizontally inclined bank of steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, a steam and water drumpositioned above'said tube bank, uptake and downtake circulators providing a natural fluid circulation between said drum and tube bank and respectively defining the front and rear walls of the upper portion of said boiler, a partition extending inwardly and upwardly'from the rear wall of said boiler and dividing the space above said tube bank and between said circulators into a pair of upflow, and downflow heating gas passages of substantial length and arranged in series, fluid heating surface in said upflow and downflow gas passages arranged and proportioned to produce a siphonal heating gas circulation successively through said upflow and downflow gas passages, and suspension means external to said drum for supporting saidpartition.

9. A steam boiler comprising a combustion chamber, an inclined bank of steam generating tubes arranged across the path'of the'heating gases leaving said combustion chamber, uptake and downtake headers connected to opposite ends of said tube bank, a steam and water drum posi- 5 tioned above said tube bank, uptake and downtake circulators connecting said drum to the tops of said uptake and downtake headers respectively,

a partition extending inwardly and upwardly from the upper portion of said downtake headers and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages, a row of partition-supporting tubes extending upwardly from said downtake headers along said partition and having their upper ends connected to said drum, heat transfer surface positioned insaid upflow and downflow gas passages, and means protecting the connections between said downtake circulators and downtake headers from the heating gases passing through said downflow gas passage.

10. A steam boiler comprising a combustion chamber, an inclined bank of steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, uptake and downtake headers connected to opposite ends of said tube bank, a steam and water drum positioned a substantial distance above the uppermost point of steam generation in said tube bank, uptake and downtake circulators connecting said drum to the tops of said uptake and downtake headers respectively and respectively defining the front and rear .walls of the upper portion of said boiler, a partition extending inwardly and upwardly from the upper portion of said downtake headers and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages, a'row of partition-supporting tubes extending upwardly, from said downtake headers along said partition so and having their upperends connected to said drum, a bank of steam superheater tubes positioned in said upflow gas passage between said uptake circulators and said partition-supporting tubes; a bank of economizer tubes positioned in said downflow gas passage between said partition-supporting tubes and said downtake circu lators and having their upper ends connected to said drum, and-a rearward extension on said partition directing the heating gases leaving said downflow gas passage away from the connections between said downtake circulators and downtake headers.

1 1,. A steam boiler comprising a combustion chamber, a row of fluid cooled ash collecting tubes extending across the upper po'rtion of said combustion chamber, an inclined bank of steam generating tubes arranged across the path of the heating gases leaving said combustion chamber, uptake and downtake headers connected to opposite ends of said tube bank, a steam and water drum positioned 'a substantial distance above the uppermost point of steam generation in said tube bank, uptake and downtake circulators connecting said drum. to the tops of said uptake and 5 downtake headers respectively and respectively defining the front and rear walls of the upper portion of said boiler, a partition extending inwardly and upwardly from the upper portion of said downtake headers and dividing the space above said tube bank and between said circulators into successive upflow and downflow heating gas passages, a row of partition-supporting tubes extending upwardly from said downtake headers-along nected to said drum, a bank of steam superheater tubes wholly positioned in said upflow gas passage between said uptake circulators and said partition-supporting tubes, a bank of economizer tubes wholly positioned in said downflow gas passage between said partition-supporting tubes and said downtake circulators and having their upper ends connected to said drum, and an explosion door arranged in the roof of said boiler directly above said upflow gas passage.

12. A steam boiler comprising a horizontally inclined bank of steam generating tubes, a steam and water drum positioned above said tube bank, uptake and downtake circulators arranged to provide a natural fluid circulation between said drum and tube bank, a series of supporting tubes having vertical portions positioned above and intermediate said tube bank and between vertical portions of said uptake and downtake circulators and ar- 3 ranged to provide a fluid circulation between said tube bank and said drum, fluid heaters positioned above said tube bank and at opposite sides of said supporting tubes, and means for supporting the adjacent ends of said fluid heaters from said supporting tubes.

13. A steam boiler comprising a horizontally in-' clined bank of steam generating tubes, a steam and water drum positioned above said tube bank, uptake and downtake circulators arranged to provide a natural fluid circulation between said drum and tube bank, a row of supporting tubes having vertical portions positioned above and intermediate said tube bank and between vertical portions of said uptake and downtake ciculators and arranged to provide a fluid circulation between said tube bank and said drum, fluid heaters positioned above said tube bank and at opposite sides of said row of supporting tubes, means for supporting the adjacent ends of said fluid heaters from said supporting tubes, and

suspension means external to said drum for supporting said supporting tubes.

14. A steam boiler comprising a horizontally inclined bank of steam generating tubes, a steam and water drum positioned above said tube bank,

rows of uptake and downtake circulators arranged to provide a natural fluid circulation between said drum and tube bank, a row of supporting tubes having vertical portions positioned above and intermediate said tube bank and between vertical portions of said uptake and downtake circulators and arranged to provide a fluid circulation between said tube bank and said drum, fluid heaters consisting of banks of multi-looped return bend tubes positioned above said tube bank and at opposite sides of said row of supporting tubes, means for supporting the adjacent ends of said fluid heaters from said supporting tubes, and suspension means external to said drum for sup- -'portingsaid suspension tubes.

15., A steam boiler comprising a horizontally inclined bank of steam generating tubes. a steam and water drum positioned above said tube bank, uptake and downtake circulators arranged to provide a natural fluid circulation between said drum and tube bank, means dividing the space above said tube bank into successive upflow and downflow heating gas passages arranged in series, a row of supporting tubes having vertical portions positioned above and intermediate said tube bank and between vertical portions of said uptake and downtake circulators and arranged to provide a imid circulation between said tube bank and said drum, fluid heaters positioned in said upflow and downflow gas passages at opposite sides of said row of supporting tubes, and means for supporting the adjacent ends of said fluid heaters from said supporting tubes.

16. A steam boiler comprising a horizontally inclined bank of steam generating tubes, a steam 5 and water drum positioned above said tube bank, uptake and downtake circulators arranged to provide a natural fluid circulation between said drum and tube bank, means dividing the space above said tube bank into successive upflow and downflow heating gas passages arranged in series, a row of supporting tubes having vertical portions posi-. tioned above and intermediate said tube bank and between vertical portions of said uptake and downtake circulators and arranged to provide a. fluid circulation between said tube bank and said drum, a fluid heater positioned in said downflow gas passage at a level lower than said drum, and means for supporting the inner end of said fluid heater from said supporting tubes.

17. A steam boiler comprising a horizontally inclined bank of steam generating tubes, a steam and water drum positioned above said tube bank, rows of uptake and downtake circulators arranged to provide a natural fluid circulation between said 25 drum and tube bank, means dividing the space above said tube bank into successive upflow and downflow heating gas passages arranged in series,

a row of supporting tubes having vertical portions positioned above and intermediate said 30 tube bank and between vertical portions of said uptake and downtake circulators and arranged to provide a fluid circulation between said tube bank and said drum, a fluid heater positioned in one of said gas passages and at a level lower than 5 said drum, means for supporting one end of said fluid heater from said supporting tubes, means for supporting the opposite end of said fluid heater from one of said rows of circulators, and suspension means external to said drum for supporting said supporting tubes.

18. A steam generator comprising a setting including a combustion chamber, a horizontally inclined bank of steam generating tubes disposed above said combustion chamber and a substantial distance below the top of said setting, a steam and water drum positioned adjacent to the top of said setting and connected to said tube bank,

a row of supporting tubes extending inwardly and upwardly from and connected to one end of said 50 tube bank and having vertical portions positioned above an intermediate portion of said tube bank and connected to said drum, a plurality of separate fluid heaters positioned above said tube bank at opposite sides of said row oi. support- 55 ing tubes, and means for supporting the adjacent ends of said fluid heaters from said row of supporting tubes.

19. A steam generator comprising a setting including a combustion chamber, a horizontally inclined bank of steam generating tubes disposed above said combustion chamber and a substantial distance below the top of said setting, a steam and water drum positioned adjacent to the top of 1 said, setting and connected to said tube bank, means dividing the space within said setting and directly above said tube bank into successive upflow and downflow heating gas passages in series, said means including a. row of supporting tubes extending inwardly and upwardly from and connected to one end of said tube bank and having vertical portions positioned above an intermediate portion of said tube bank and connected to said drum, a plurality of separate fluid heaters positioned in said upflowand downflow gas passages at opposite sides of said row of supporting tubes, and means for supporting the adjacent ends of said fluid heaters from said row of supporting tubes.

20. A steam generator comprising asetting including a combustion chamber, a horizontally inclined bank of steam generating tubes disposed above said combustion chamber and a substantial distance below the top of said setting, a steam and water drum positioned adjacent to the top of said setting and connected to said tube bank,

means dividing the space within said setting and directly above said tube bank into successive upflow and downfiow heating gas passages arranged in series, said means including a row ofsupporting tubes extending inwardly and upwardly from and connected to one end of said tube bank and having vertical portions positioned above an intermediate portion of said tube bank and connected to said drum, a plurality of separate fluid heaters positioned in said upflow and downfiow gas passages at opposite sides of said row of supporting tubes, the fluid heater in said upflow gas passage comprising a bank of returnbend steam heating tubes, and means for supporting the fluid heaters in said upflow and downflow gas passages from said row of supporting tubes.

21. A steam boiler comprising an inclined bank of steam generating tubes, a steam and water drum positioned above said tube bank, spaced groups of vertically extending uptake and downtake circulators arranged to provide a fluid circulation between said drum and the corresponding ends of said tube bank, a group of suspended supporting tubes having vertically extending portoins above said tube bank and between said groups of circulators and having their ends connected for a fluid circulation therethrough, an auxiliary fluid heater positioned above said tube bank and between said groups of circulators, and means for jointly supporting said fluid heater from, said supporting tubes and circulators.

22. A steam boiler comprising an inclined bank of steam generating tubes, a steam and waterv drum positioned above said tube bank, spaced groups of vertically extending uptake and downtake circulators connecting said drum to the corresponding ends of said tube bank, a partition extending transversely of said tube bank and dividing the space above said tube bank and between said groups of v uptake and downtake circulators into a. pair of heating gas passages, a

group of suspended supporting tubesextending upwardly in heat absorbing relation with said partition and having their ends connected for a fluid circulation therethrough, a bank of looped fluid heating tubes positioned in one of said gas passages, and means for supporting said looped tube bank from an adjacent group of circulators and said supporting tubes.

23. A steam boiler comprising an inclined bank of steam generating tubes, a steam-and water drum positioned above said tube bank, spaced rows of vertically extending uptake and downtake circulators arranged to provide a fluid circulation between said drum and the correspond- 7 ing ends of said tube bank, a partition extending transversely of said tube bank and dividing the space above said tube bank and between said rows of circulators into a pair of vertical heating gas passages, a row of tubes having vertical portions supporting said partition and having their ends connected to provide a fluid circulation between said tube bank and said drum, a fluid heater positioned in one of said gas passages, means for supporting one end of said fluid heater 10 from said partition-supporting tubes, means for supporting the opposite end of said fluid heater from one of said rows of circulators, and suspension means external to said drum for supporting said partition-supporting tubes.

24. A steam boiler comprising an inclined bank F of steam generating tubes, a steam and water drum positioned above said tube bank, groups of uptake and downtake circulators connecting said drum to the corresponding ends of said tube bank, a partition dividing the space above said tube bank and between said circulator groups into a pair of heating gas passages, a row of suspended fluid heating tubes extending upwardly in heat absorbing and supporting relation with said partition and having their upper ends connected to said drum, a bank of multiple-looped fluid heating tubes positioned in the gas passage adjacent said uptake circulators, means for supporting said looped tube bank from said uptake circulators and partition-supporting tubes, a second bank of multiple-looped fluid heating tubes positioned in the other gas passage, and means for supporting said second looped tube bank from said partitionsupporting tubes and downtake groups of circulators into a pair of heating gas passages, a row of partitions-supporting tubes ex- 00 tending-upwardly from said downtake headers in heat absorbing relation with said partition and having their upper ends connected to said drum, a bank of multiple-looped fluid heating tubes positioned in the gas passage adjacent said up take circulators, means for supporting said looped tube bank from said uptake circulators and partition-supporting tubes, 2, second bank of multiple-looped fluid heating tubes positioned in the other gas passage, means for supporting said sec- I 0nd looped tube bank from said partition-supporting tubes and downtake circulators, and suspension means external to said drum for support- I ing said partition-supporting tubes.

- DAVID S; JACOBUS.

ROBERT K. BEHR. 

